The invention is directed to a process for embedding highly and average active, especially tritium containing, granular and lumpy solid waste in a metal matrix for the purpose of final storage.
In the operation of nuclear reactors and other industrial nuclear plants, particularly in the reprocessing of spent fuel elements from light water reactors, there accumulates high or average active solid wastes, for example, scrap, apparatus parts, fuel element top and bottom pieces, fuel element jackets, spacers, springs, bolts, and other small parts which must be conditioned and stored in such manner that the environment is not endangered.
According to the present state of the art, this is made possible by embedding the radioactive solid waste in concrete and later intercalation in a suitable geological formation.
Average and high active waste products for this purpose must be conditioned and stored in such manner that the central temperature of the product does not exceed 90.degree.-95.degree. C. The dilution of the waste necessary for this and the increase of the storage volume obtained is disadvantageous for the covering with concrete. A further disadvantage is that tritium can be set free from the concrete covered solid wastes, particularly from fuel element jackets.
From the German OS Nos. 26 28 144 and 2 717 389, there are known processes which embed the waste in a metal matrix. The embedding takes place by filling the hollow space between the solid wastes with a molten metal consisting of aluminum or low melting metals such as lead, tin, zinc, copper, or metal alloys.
It is also known, e.g., to embed fuel element jackets in glass or by melting radioactive solid waste with additives to solidify it to a compact block.
All of these processes have the disadvantage that by the use of elevated temperatures during the solidification processes there are set free volatile radio-nuclides as, e.g., tritium or ruthenium which are separated from the waste gas and must be separately eliminated.
Therefore, it was the problem of the invention to develop a process for embedding radioactive wastes in a metal matrix in which no elevated processing temperatures need be used and in which simultaneously the thermal conductivity and the ability of the final product to retain tritium is improved, and the leaching out of radionuclides is reduced in case of accident.